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Author Topic: Air France 447 - many lessons to be learned  (Read 15296 times)
ORD Don
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« on: July 05, 2012, 11:02:39 AM »




             Yet another crash that "never should have happened".  So sad.....


             http://www.cnn.com/2012/07/05/world/europe/france-air-crash-report/index.html?hpt=hp_t1

             http://www.cnn.com/2011/10/14/world/americas/af447-transcript/index.html

             http://avherald.com/h?article=41a81ef1/0080&opt=0
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derekjackson
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« Reply #1 on: July 05, 2012, 01:52:04 PM »

Here's the link to the official BEA report and appendices in english, it includes the complete CVR transcript in the appendix.

http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php
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ORD Don
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« Reply #2 on: July 07, 2012, 10:55:10 AM »





        Question:  The pilots of AF 447 apparently had no idea of what the aircraft was doing.  Wouldn't the altimeter

                          have shown them that they were falling out of the sky ?   Also, I was wondering what the pilots out

                          there think.  Was this more of a mechanical thing ( systems peculiar to the A330 ) or more of a cockpit

                          management issue.  I understand that, like almost all accidents, it was a combination of many things....

                                                                                                                                                         Thank you
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derekjackson
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« Reply #3 on: July 07, 2012, 11:48:18 AM »

(I'm not a pilot)

Yes, they had working altimeters. It seems they realized at 10,000 feet they were falling fast.

I think poor CRM is at the heart of the accident rather than an A330 issue (although the pitot probes were later upgraded). They never called for the unreliable airspeed checklist and seemingly ignored or didn't trust the stall warnings for a long time.
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joeyb747
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Nothing Like A 747!


« Reply #4 on: July 09, 2012, 10:31:46 PM »

I agree with dereckjackson. Poor CRM was defiantly a factor, but the pitot tubes were a pretty big factor as well. The age old saying is that an accident is a chain of events, with never one factor. Break the chain, and the accident doesn't happen. If Air France had changed the pitot tubes on that airframe (Air France had the new tubes and the time of the crash. This airframe was scheduled for the upgrade with-in the next month.), or the weather hadn't been bad, or if they had flown around the storm, or if they had a reference point like the horizon, or if it was simply day time, they may have been able to fly the airplane, and deal with what the airplane was throwing at them. and it all goes back to  NORMAL LAW vs. ALTERNATE LAW. When the computers lose a parameter such as the airspeed information from the pitot tube, the airplane switches modes. In NORMAL LAW, the airplane protects itself in several different dimensions. One such protection is stall, meaning, quite simply, the pilot can pull the side stick to full back deflection, and the airplane WILL NOT STALL. However, when the airplane switches to ALTERNATE LAW, most of those protections are lost. The autopilot and auto throttle are instantly disconnected, leaving the pilot to fly the airplane, as well as deal with the annunciator panel lighting up like a Christmas Tree, and trying to figure out which warnings are real, which are not. Which gauges are accurate, which are not. Out over the ocean, in bad weather, at night, add into that the failing computer system on the airplane, overwhelming.

At 2:10:22, the copilot sitting in the left seat knew the airplane was in ALTERNATE LAW. They both should have known that the airplane can be stalled, but they continued to climb, as indicated by the conversation around the 2:12:27 mark.

NORMAL LAW:
"High Angle of Attack Protection (alpha):
When alpha exceeds alpha prot, elevator control switches to alpha protection mode in which angle of attack is proportional to sidestick deflection.
Alpha max will not be exceeded even if the pilot applies full aft deflection"


ALTERNATE LAW:
"All protections except for load factor maneuvering protection are lost."
"The airplane CAN be stalled in Alternate Law."

From:
http://www.airbusdriver.net/airbus_fltlaws.htm
« Last Edit: July 10, 2012, 08:34:30 AM by joeyb747 » Logged

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notaperfectpilot
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« Reply #5 on: July 10, 2012, 06:31:18 AM »

I am a student private pilot, so, I can't "analyze" too much (being an "outsider" in the ATP world) other then what I can observe  from the information, especially on the AvHerald. 

I really think that you can boil the problem down to one thing. And that is, lack of situational awareness. I think that both pilots really didn't have a complete idea of exactly what was going on...I think that this is clearly shown in the cockpit transcripts. But, I also think that there was another thing that was involved and that is, too much trust in technology. I think that the one pilot knew that the plane had switched to an alternate mode but I don't think that it quite clicked as shown by him holding the stick back for over 2 minuets. I think that he still thought that he couldn't stall the plane regardless of what he did, even though that he acknowledged the computer switch over. 

Oh, and in reference to joeyb7474 and derekjackson, I would agree that poor CRM is a big factor and I guess that I just restated (above) what joeyb747 has already said! shocked

Just my two cents  grin
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ZetaByte
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« Reply #6 on: October 10, 2012, 08:29:25 PM »

Previous poster was absolutely correct - this accident should never have happened. Someone on that flight deck needed to go back to aerodynamics 101. With the attitude of the aircraft 12-15 degrees ANU, and the VVI showing 10,000 FPM down, the list of probable causes is really short. Can you shout STALL! Someone needed to remember basic pitch/power instrument principles, stick the attitude at, or slightly below the horizon, and check for maximum thrust. The airplane would have started flying again, with or without an airspeed indication. Once under control, FMS ground speed could have been employed to fly a final approach to the nearest airport where they could have fixed the pitot tubes. Sadly, this isn't limited to Airbus. I've read reports where pilots of small single engine aircraft have crashed and died because a mud wasp had caused a blockage of their pitot tube. No student of mine ever solo'ed without demonstrating an ability to fly a traffic pattern with the airspeed indicator covered up.
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joeyb747
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Nothing Like A 747!


« Reply #7 on: October 11, 2012, 08:36:38 AM »

Sadly, this isn't limited to Airbus. I've read reports where pilots of small single engine aircraft have crashed and died because a mud wasp had caused a blockage of their pitot tube.

Large and small aircraft alike have fallen to the mud wasp. Birgenair 301 was a Boeing 757-225 that crashed in 1996 after leaving Puerto Plata in the Dominican Republic. The probable cause listed in the report was a blocked pitot tube, most likely blocked by the nest of mud dauber wasps.
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SantiBailors
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« Reply #8 on: January 13, 2013, 08:07:28 AM »

(Sorry I didn't find a good way to get the URL to show as a URL instead of as the video itself; the URL would be wwwREMOVE.youtube.com/watch?v=2ei-qss0sPQ, remove the word REMOVE)

It is my understanding that one of the biggest questions is why the pilots totally ignored all the loud and continued stall warnings. Had they even just wondered whether the warnings were worth some credit and thus checked if they actually were in a stall, I don't think they might have concluded that they weren't in a stall.

Unlike many, I do not feel like quickly pointing my finger at the pilots and wonder how can anyone miss those warnings, how could they have panicked to the extent of ignoring those warnings, etc. Nobody who can clear a middle-school exam can be stupid enough not to care about such warnings, and I do not believe that 2 or 3 experienced, skilled, trained pilots can panic at the same time to the extent of ignoring those warnings for such long time.

I always thought they must have had a reason - although a wrong one - for not even considering the possibility that the stall warnings were worth some credit during the whole descent.

The only clue I found about what that reason could be, is in this documentary:



shot shortly after the accident, where at 18:13 a French pilot representative of a pilots union clearly confirms that the Air France procedure instructs to respect the stall warnings while the Airbus procedure instructs to ignore the stall warnings.

Let's try for a moment not to mind his patronizing laughter and the weirdness of the idea that Airbus would manufacture a stall warning system and then instruct to ignore it (there are probably missing details, maybe the Airbus manual meant the warning should be ignored at high altitude, or something like that). If it's true that in such situation one procedure instructs to do one thing and the other procedure instructs to do the opposite thing, then wouldn't that matter a lothuh
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I'm just an air safety fan with no specific aviation knowledge.
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